The objective of this acquisition is the continuation of work which was performed under Contracts N01-CP-41057, -41058, and -41059. The purpose of this contract is to provide for the need of the EEB, DCE, NCI to rapidly evaluate hypotheses concerning the environmental causes of cancer. These hypotheses may arise from clinical observations, epidemiologic studies or laboratory experimentation. This contract will utilize the services of a Pre-Paid Health Plan (PPHP) for a rapid and relatively inexpensive way to accomplish this for some environmental exposures utilizing already-recorded information on large groups of patients with a particular cancer and on a comparable series of persons without the disease.